A blation of persistent atrial fibrillation (AF) remains challenging, particularly as the duration of continuous AF before the procedure increases. Attainment of durable pulmonary vein (PV) isolation remains a fundamental goal in this population; continuous retriggering from focal peri-PV sources (both automaticity and localized reentry) as a potential mechanism for maintaining persistent AF was documented more than a decade ago. 1 An area of continuing debate centers on the extent of additional atrial ablation outside the PV antra required for long-term maintenance of sinus rhythm. Two studies published in this issue of Circulation: Arrhythmia and Electrophysiology highlight important clinical aspects of this debate.
Articles see p 287, 295, and 442Inoue and colleagues 2 report long-term follow-up of catheter ablation in 263 patients with persistent AF (mean duration of continuous AF, 11 months; Ͼ1 year in 50%). To identify triggers that may perpetuate AF, cardioversion was performed at procedure onset, followed by short-duration isoproterenol infusion if needed, to provoke immediate recurrence of AF. The immediate recurrence of AF occurred in 70 (27%) of 263 patients, one third arising from non-PV foci. These triggers were then targeted for ablation (successful in all peri-PV foci, but in only 6 of 23 patients with non-PV triggers). All patients subsequently underwent PV isolation, and 72% had additional non-PV left atrial ablation. At the last follow-up of 17 months (38% of patients receiving antiarrhythmic drugs [AADs], multiple procedures in Ϸ30%), 90% of patients were in sinus rhythm, although 16% continued to have paroxysmal episodes. Immediate recurrence of AF was associated with a greater risk of recurrent persistent AF during follow-up, predominantly a result of inability to localize and eliminate non-PV focal triggers.In a randomized trial of ablation for persistent AF, Dixit and coworkers 3 evaluate 3 strategies for ablation of persistent AF: (1) PV isolationϩablation of non-PV triggers elicited by cardioversion and isoproterenol infusion (standard protocol), (2) standard protocolϩempirical ablation at sites that commonly harbor non-PV foci (superior vena cava, crista terminalis, peri-coronary sinus os, and inferolateral mitral annulus), and (3) standard protocolϩablation of sites with complex fractionated electrograms as identified by automated algorithm (cycle length, Ͻ120 ms). Single-procedure efficacy (freedom from any atrial arrhythmias without AAD) was 49%, 58%, and 29% at 1 year in the 3 groups, respectively, and 53%, 62%, and 51% at final follow-up, respectively. The latter included repeat ablation using the standard protocol in 37% of patients. Additional AAD therapy in an unspecified number of patients, and a more lenient (but clinically reasonable) definition of rhythm control, led to efficacy rates of 64%, 70%, and 43% at 1 year and 80%, 82%, and 80% at the end of the study (mean, 19Ϯ9 months after last ablation), respectively. The first 2 strategies resulted in significantly better initi...